The average height of a group of girls was 113 cm. After 8 boys with a total of 1000 cm joined the group, the average height of all the pupils increased to 119 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Pupils |
Number |
1 u |
8 |
1 u + 8 |
Value |
113 |
? |
119 |
Total value |
113 u |
1000 |
119 u + 952 |
(a)
Average height of boys
= 1000 ÷ 8
= 125 cm
(b)
Total height of pupils
= 119(1 u + 8)
= 119 u + 952
Total height of girls and boys = 113 u + 1000
119 u + 952 = 113 u + 1000
119 u - 113 u = 1000 - 952
6 u = 48
1 u = 48 ÷ 6 = 8
Number of girls = 8
Answer(s): (a) 125 cm; (b) 8